This invention relates to a photofluidic interface that transduces optical control signals to pneumatic or hydraulic control pressures using only fluidic and thermal devices for its control system. A typical application would employ a laser or light emitting diode (LED) modulated light source to send carrier wave control signals through an optical fiber to a remote location where the photofluidic interface would produce analog pressures for driving a valve, piston or other actuator. Thus, beyond the point of the modulated light source, the control system will require no electronic devices or electrical power to operate.
The significant advantage of this invention over the prior art is that it provides a means for the elimination of electronic devices to accomplish the optical to pneumatic or hydraulic transduction, which is very important when the operation of electronic devices may be hazardous, or undesirable for other reasons.
It is known in the prior art to use a photo diode to receive an optical signal and convert it to an electrical signal. This electrical signal is then converted into mechanical motion which in turn controls a pneumatic or hydraulic valve, switch or actuator. This scheme is sensitive to environmental hazards because the photo diode can become inoperative or be destroyed in the presence of electromagnetic radiation, extreme temperatures, or shock. The photo diode output current in this alternative must also be converted to a useable voltage to drive a solenoid or other actuating device, thus requiring that electrical power be available at the remote control station or location. This can present a threat to the reliability of the system due to the susceptibility of the system to power failures, radiation and extreme temperatures. Also, the requirement for the use of electrical power can threaten the safety in hazardous environments such as in the presence of explosive gases which could be detonated by electrical current.
By contrast, the photofluidic interface is much less susceptible to radiation, extreme temperatures and shock. It requires no electrical power at the remote station or location and therefore presents no spark-detonation hazard. Further, the photofluidic interface employs no moving parts. It, therefore, benefits from the increased reliability similar to other fluidic devices.